Compressor



' Jan. 2, 1945. w. R. FREEMAN COMPRES SOR Filed Dec. 11, 1942 2 Sheets-Sheet l You INVENTOR .R.FREEMAN ATTORNEY Patented Jan. 2, 1945 COMPRESSOR Walter R. Freeman, Clayton, Mo., asslgnor to Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Application December 11, 1942, Serial No. 468,635

' compressors.

12 Claims. (Cl. 239-192) My invention relates to compressors for placing fluids under pressure and more particularly to compressors of the reciprocating piston type.

One of. the objects of my invention is to produce an improved compressor of the type referred to which will compress a fluid more efflciently; will be easier to lubricate, and will operate at cooler temperatures than prior known Another object of my invention is to produce a compressor of the reciprocating piston type in which a piston does not perform any compressing operation upon the fluid to be compressed until said fluid has been placed under a superatmospheric pressure by having its volume-added to a volume of fluid already compressed.

Still another object of my invention is to produce an improved reciprocating piston type compressor embodying valve means which will permit a newmethod of compressing comprising steps whereby a volume of previously compressed fluid and a volume of fluid to be compressed will are mounted on the same crank arm of the crankshaft and, therefore, as the crankshaft ro- 'tates, one piston will be moved inwardly in its cylinder as the other ,is moved outwardly in its cylinder and vice versa.

The outer end of cylinder 4 has an inlet port I2 for admitting air or other fluid 'to be compressed to chamber 13 ahead of piston 8. An inlet valve element [4 controls the inlet port and is biased to closed position by a spring l5. The

As best shown in the enlarged view of. Figure 2,. piston 8 is provided with a passage 20 through its head which is controlled by a slide valve elebe connected to each other and allowed to have their pressures equalized and then the total volume will be compressed to the volume which the previousl compressed fluid had prior to being connected to the volume of fluid to be compressed.

Yet another object of my invention is to produce a compressor of the reciprocating 'piston type which will be capable of delivering greater volume of compressed fluid at a lower temperature than prior known compressors having the same piston area and stroke.

Other objects of my invention will become apparent from the following description taken in connection with the accompanying drawings in which Figure 1 is a sectional view of a compressor embodying my invention; Figure 2 is an enlarged view of the. piston rod controlled valve mechanism; Figure 3 is a sectional view similar to Figure 1 but showing the pistons and valves in other positions; and Figure 4 is a view of a single piston compressor.

Referring to Figures 1 to 3, my improved compressor comprises a casing I having oppositely extending portions 2 and 3 which are provided with cylinders 4 and 5, respectively. The casing between the cylinders is hollow to provide a chamber 6 and-journaled in the casing and extending across this chamber is a crankshaft '1.

Cylinder 4 has mounted therein a reciprocable piston 8 connected to the crankshaft by a piston rod-9. Similarly, cylinder 5 has mounted there in a r eciprocable piston in connected to the crankshaft by a piston rod ll. Both piston rods valve element 25 will be open. Valve element 25 gagement-withthe piston head surface.

piston [0 .also has a passage 24 through its headment 2| cooperating with the inside surface of the head. The opening and closing of the valve element is controlled by a projection 22 on the piston'rod which fits in a recess-in the element.

A leaf spring 23 biases the valve element into en- The inder, asshown in Figure 1, and the crankshaft rotates in a clockwise direction, as indicatedby the arrow, then valve element 2| will open and valve element 25 will remain closed as .piston '8 moves toward the outer end of its cylinder and piston Ill moves toward the inner end of its cylinder. As piston l0 begins to move toward the outer end, valve element 2| will open quickly as a given angular movement of the crankshaft at this point results in a large angular movement of the piston red but small piston movement. When piston 8 moves from the outerend toward the inner end of its cylinder and piston I0 moves from the inner end toward the outer end of its cylinder, valve element 23 will remain closed and will open quickly at the beginning of the outward movement of piston l0. 7 Chamber 6 between the cylinders is provide with an outlet port 28 controlled by a check valve 29. The port communicates with a conduit 30 leading to a storage tank or a device to be operated by the compressed air or other fluid. Oil is placed in the chamber to lubricatethe crankshaft, pistons, and other moving parts.

Referring now to the operation of the compressor, valves 2| and 25 wi1l be closed when the pistons ar in the positions shown in Figure 1. Air under atmospheric pressure will be in chamber I 3 having been drawn in through the inlet port l2 by the movement of piston 8 to the inner end of its cylinder. Previously .com-

pressed air is in chamber 6.

As the crankshaft rotates in the direction of the arrow, valve element 2| will be opened at additional quantity of air added to it. As pistons 8 and, Ill now continue .to .move to the left, the air in the intercommumoating .chambers 6 and [3 will be compressed by piston 10. Figure .3 shows the positions of the parts of the compressor as the compressing takes place. After the pressures of air in chambers .6 and I ,3 equal- .ize and piston .-8 continues to move to the left,

the airin chamber l3 will .be transferred through t e op passa e 20. Pist n 8 will do no compressing due to the open condition of the passage. During the movement of piston I-ll to the left, air at atmospheric pressure will be drawn into chamber I?! through the inlet port I6.

When pistons 8 and .Ill reach the left end of their cylinders, valve element 25 will still be closed, and the valve element .21 will become closed. The volume of compressed air will be the same but since it has had added to it a volume of air (that of chamber 1.3 when piston 8 was at the left .end of its cylinder) the pressure will be increased and some-of it will cause an increase in the pressure of the air in the storage tank by flowing out through the outlet o chambe 6- I As pistons .8 and Ill now move to the right by .continued rotation of crankshaft, valve element 2| will remain closedand valveelement 25 will open. The compressed air in chamber 6 will now flow into chamber .l.| filled with uncompressed air and the air in both chambers will have th same pressure.

This volume of to the previously compressed air and placed under pressure. The clearance between the piston at th end of its stroke-and the cylinder can be very small. This will permit very little air under pressure to be lost when the piston moves away from the cylinder head and air at atmospheric pressure is drawn in. Also, this lost air .under pressure will not be under as great a pressure as would be the case where the compressing took place between the pistonv head and cylin- .der head as in prior compressors. It is also to be notedthat since compressing does not take place in chambers l3 and. I1, thes 'cham-bers will be cooler and, therefore, there willbe less ex ansion of the air as it is drawn in from the atmosphere. By keeping the air to b compressed cool, it will have a greater density and consequently less work will be necessary to compress it to a predetermined pressure.- Another feature to be noted from the method of compressing the fluid is that the entire stroke of the piston is employed only to increase the pressure of the previously compressed air to the final air will now be compressed by piston 8 mov.- 5.,

ing to the right, thus raising the pressure of the air in chamber 5. During the movement of piston 8 to the right, air under atmospheric pressure will be drawn into chamber l3 and b ready to be added to the previously compressed air as the cycle of operation is repeated.-

From the operation of the compressor just described, it will be apparent that the compressing operation takes plac in a body of air in a. large chamber 6. The heat resulting from the compression of the air will thus be able to be dissipated over a larger surface and, therefore, the

outlet temperature of the compressed air will be cooler than that of a compressor'of the conventional reciprocating type in which the air is compressed by the head of a. piston traveling to the end of a cylinder having an outlet therein.

The compressor will also be very emcient because substantially all of the air drawn into chambers l3 and I1 tobe compressed will be added 0 ends of the cylinders.

pressure and not to raise the pressure of air from atmosphere to the final pressure as in the conventional method of compressing. The work .done is the same due to the different volumes com-pressed but such work is more. evenly distributed throughout the stroke of the piston in.- stead of being-concentrated mostly at the end of the stroke. Testshave shown that the improved compressor will compress more air with the same amountof work than known reciprocating pis- .ton type compressors having the same size pis- ,ton and the same piston stroke. Although only two compressing pistons are shown, .a greater number can be employed without changing the method of compressing.

The compressor will be lubricated by the oil in chambert being splashed about bythe crankshaft. No bad carbonization of this oil will occur on the heads of the .pistons and the heads of the cylinder since compressing is not done there. tween and, therefore, no high temperatures at such localities to cause carbonization. The pistons also will not be directly forcing ,oil laden air out of the compressor. Any oil laden air that gets into chambers l3 and 11- will return tochamber vIi when the pistons move to the outer Any oil laden air that passes the outlet port 28 can be passed through an oil separator and the separated oil returned to chamber 6. It is thus seen that very little oil will be lost and particularly very little by carbonization. The pistons will also be better lubricated because of less destruction of the oil in the cylinder heads. It is also to be noted that by substantially eliminating carbonization or caking of oil on the piston heads and cylinder heads, no added clearance therebetween need be allowed which, as already noted, results in increased efliciency not possible in prior known compressors of the reciprocating piston type.

A compressor in which only the single piston' or the piston. There will be no compressing during the outward stroke or the single piston as is done in the two piston compressor where the eliminated second piston acted on the added new body of air.

Being aware of the possibility of modifications in the particular structure herein described without departing from the fundamental principles or I my invention, I do not intend that its scope be limited except as set forth by the appended claims. I

Having fully described my invention, what I claim as new and desire'to secure by Letters Patent oi! the United States is:

1. In a compressor, two chambers, a movable valve for placing thechambers in communication with ea other, positive means for so coordinating the operation of the valve and the movement, of the movable wall that when thewall moves in one direction the valve will be closed to thereby permit the wall to compress the fluid in the chamber the volume of which is being decreased by the wall movement and when the wall moves in the opposite direction the valve will be opened' and maintained in an open condition throughout the movement in said opposite direction to permit the fluid in the chambers to inv terchange and assume equal pressures without any appreciable compressing action by the wall during said opposite direction movement, and

.-means for permitting fluid to be compressed to enter the chamber which is having its volume increased during the compressing movement of the wall.

'2. In a compressor, two chambers divided by reciprocatins the piston, means forming chambers on each side ofthe piston, means for pertwo other chambers, two movable members one of which forms a'movable wall between one of said two chambers and the compressing chamwall between the chambers, means'comprising a thereof.

a movable wall, means for moving said wall to vary the volumes of the chambers, valve means permitting fluid which is to be compressed to enter one chamber only when the wall is moved to decrease the volume of the other chamber, means comprising valve means u der the control of the wall moving means for placing the chambers in communication with each other irrespective of any difference in pressure when the wall is moved to decrease the volume of the chamber to which fluid to be compressed 'has been admitted, and

means for compressing the fluid in both cham-- piston during its stroke to increase the volume of ber and the other of which forms a movable wall between the other of said two chambers and the compressing chamber, means for moving said members simultaneously so that one of the two chambers will increase in volume while the other decreases and vice versa, an inlet check valve for each or said two chambers, means compris ing a valve associated with each of the two chambers for placing each of saidtwo chambers in communication with the compressing "chamber, 'and'means for positively controlling the opening and closing or each valve by the mov- 'ing means for the members, each valve bein open only during theperiod in which the movable member of the chamber-with which it is associated is being moved todecrease the volume 7. In a compressor, two cylinders each communicating with a common compressing chamber at one of. its ends, pistons in the cylinders, means for reciprocating the pistons so that one moves toward its cylinder head while the other moves away from its cylinder head, inlet valves for admitting fluid to the head portions of the .cylinders as the pistons move away from said head portions, and means comprising valves positively controlled by the reciprocating means for permitting the head portion of each cylinder to communicate with the compressing chamber during the movement of the piston therein toward the cylinder head irrespective of any differences in pressure and for preventing said communication during the stroke of said piston in the OP posite direction.

8. In acompressor, two cylinders,pistons reciprocable therein, a crank shaft and piston rods for reciprocating the pistons simultaneousl 'in opposite directions'in the cylinders, a common chamber communicating with an end of each cylinder, an inlet valve for each cylinder for admitting fluid to be compressed to the cylinder ahead of the piston therein during movement said one chamber, and means comprising valve means under the control of the piston reciprocating means for placing the chambers in communication with each other only during .the return stroke of the piston. I

4. In] a compressor, a cylinder, a piston therein, means for reciprocating the piston, means forming chambers on each side of the piston,

means for permittingfiuid to be compressed to.

enter the chamber on one side of the piston during its stroke to increase the volume of said one chamber, valve means for placing the chambers I in communication with each' other, and means for causing said valve means to be actuated to an open .position by the piston reciprocating means and to remain in open position only during theof the piston toward the end communicating with the common chamber, means comprising a valve for placing the portion of a cylinder ahead of thepiston therein in communication with the common chamber, and means positively operable by the piston rods ior opening the last named valves, each valve being open only when its opcrating piston rod moves the piston in the cylinder with which it is associated in a direction to. decrease the volume of the portion of the cylinder ahead of the piston.

ter the inlet only as the volume .01 the one chamber is increased by movement of the wall, a passage between the chambers, a valve for said passage which when open permits flow of fluid between the chambers in iroth and when closed prevents flow of fluid to the chamher having an inlet, and means positively onerable by the wall moving means to: opening the passage valve only when the volomeoi said one chamber is decreased by movement or the wall.

10. In a compresxm-a non-oompruling-chamher, a compressing chamber. a mrating movable wall between the chambers meanl tor moving said wall to vary the volumes of the chembers, an inlet to the non compnosing chamber, a valve for the inlet permitting fluid to be compressed to enter the nonmempreeslng chamber only when the volume of said chamber 1s mcreesed, a passage permitting communication between the chambers, a valve for controllin said passage, and means positively controlled by the wall moving means tor causing said last named valve to be open irrespective of any dinerence in pressure to permit new :0! fluid through the passage in both direction: when the movable wall is moved to decrease the'vohi'me of the noncompressing chamber andincmue the volume of the compressing chamber whereby the pressures of the fluid in both chamber! will equalize and for causing said .last named valve Ito be closed to prevent flow of fluid irom'the compressing chamber to the non-compressing chamber when the movable wall is mover: to some increase in names an inlet for the cylinder ahead or the piston,

a check valve for the inlet, a passage through the piston, a closure valve for the passage, and

' ,means positively controlled by the reciprocating means and operable when the piston is moved forwardly in the cylinder for opening the closure valve to permit interchange of fluld in both directions between the portion of the cylinder ahead of the pistonand the compression chamber at the rear thereof.

12. In a compressor, a cylinder, apiston in the cylinder, means for reciprocating the piston comprising a crank and pistonrod, a compression chamber at the rear of the piston, an inlet for the cylinder ahead of the piston, a check valve for the inlet, a passage through the piston, a closure valve for-the passage, and means posh tively controlled by the crank and piston rod during forward movement of the piston for maintaining the valve open to permit interchange oi. fluid in both directions between the cylinder ahead of the piston and the compression chamher at the rear thereof.

WALTER R. FREEMAN. 

